Numerous types of electrodes have been used in the medical field, for both diagnostic applications such as EKG, EMG and EEG and therapeutic applications such as electrical muscle stimulators, transcutaneous electrical nerve stimulators and iontophoresis drug delivery stimulators. The need to place electrodes at the correct locations has long been recognized as important as well as the need to use electrodes of a correct size. The requirements for correct placement and correct size become even more important for electrical signals that are monophasic or asymmetrical in shape. Two or more electrodes of the same or varying sizes are individually placed on the patient undergoing some form of electrotherapy or diagnostic procedure. In many cases, optimum results are not obtained because the electrodes are not placed on the subject in the correct fashion.
It is often necessary to establish a localized electrical contact with the external body surface of a living subject. Such contact is typically achieved by the use of electrically conductive electrodes having extended surface areas placed in electrical contact with a desired portion of an external body surface through an intermediate electrode gel, liquid or other preparation designed to ensure good and continuous electrical contact between the living body surface and the conductive electrode surface. Such electrical connections to living subjects are now commonly required for therapeutic and diagnostic applications in both medical and veterinary usage. For example, electro-therapeutic stimulation has now been recognized to promote the healing of bones and other body tissues and/or to have other advantageous physiological effects. Many diagnostic techniques (e.g., electrocardiograms) also require electrical connections to body surfaces so as to monitor electrical body surface potentials.
U.S. Pat. No. 3,848,608 discloses a cutaneous stimulator which includes a plurality of pairs of electrodes and ventilation holes located in a ground plane between each adjacent pair of electrodes. This stimulator does not provide an arrangement of electrodes relative to the holes such that therapeutic current density is particularly determined in the vicinity of the holes. Further the arrangement disclosed in this reference does not necessarily provide electrode location control or easy access to the injury being treated.